Fig 1. 498:1 & 2-1868 wood-burning stove, glazed earthenware tiles

Fig 1. 498:1 & 2-1868 wood-burning stove, glazed earthenware tiles, Germany, 16th century.

The free-standing structure was designed as a wood-burning stove, stoked and ventilated from the back through two holes in the wall, so it could heat a room without filling it with smoke and fumes. It is composed primarily of relief-moulded lead-glazed earthenware and painted tin-glazed earthenware stove tiles.  The deep tiles are both highly decorative and functional, constructed to retain heat effectively. The stove (with two tiles dated 1577) was made in Villingen, Germany by Hans Kraut.

Fig 2 Side view of stove

Fig 2 Side view of stove

Fig 2 Side view showing the combination of different relief-moulded lead-glazed earthenware and painted tin-glazed earthenware stove tiles.

Fig 2a. side view of stove

Fig 2a. side view of stove

Fig 2 Side view showing the combination of different relief-moulded lead-glazed earthenware and painted tin-glazed earthenware stove tiles.

Fig 3 Detail of deteriorating old repair to corner of a tin-glazed earthenware tile, discoloured paint and chipped plaster fillings.

Fig 3 Detail of deteriorating old repair to corner of a tin-glazed earthenware tile, discoloured paint and chipped plaster fillings.

Condition of the stove

Structural damage to the stove ranges from small chips along the edges of the tiles through to the complete loss of a component, as for example one of the legs. Past restorations include the bonding of broken tiles and the filling and retouching of areas of loss.

Fig3a. V&A no. 498-1868, Feb0508

Fig3a. V&A no. 498-1868, Feb0508, sideview.jpg

Large areas of loss, such as the leg, have carved wood replacements. The majority of the old repairs are securely attached but have inevitably deteriorated since they were made; the paint medium has yellowed and fillings have become chipped.

Fig 4 Detail of deteriorating old repairs to edge of lead-glazed tiles: discoloured paint and chipped plaster fillings.

Fig 4 Detail of deteriorating old repairs to edge of lead-glazed tiles: discoloured paint and chipped plaster fillings.

In addition to the structural damage, a thick layer of dirt obscured the decoration on the tiles.

Fig 4a Detail of dirt that has accumulated on an old wax coating on the arm of the seat

Fig 4a Detail of dirt that has accumulated on an old wax coating on the arm of the seat

Three-dimensional objects, especially with deep relief, provide plenty of surfaces for dust and dirt to collect. In preparation for re-display, the stove needed to be made safe to transport and present 'in the round'. The majority of existing repairs were deemed stable; therefore attention was focused on treating the unstable areas and cleaning the object. 

Fig 5 & 5a The surface is disfigured by superficial dust and dirt. Detail of cleaning in progress – showing disfiguring accumulation of dirt (left hand side) & cleaned glaze (right hand side)

Fig 5 & 5a The surface is disfigured by superficial dust and dirt. Detail of cleaning in progress – showing disfiguring accumulation of dirt (left hand side) & cleaned glaze (right hand side)

Cleaning of the stove

A relatively straightforward cleaning process was proposed. However, an object of this size does require adequate time, space and a team of people to do it justice.  Students from the Conservation of Ceramics and Related Materials Course at West Dean College, West Sussex assisted the Ceramics and Glass Conservation Studio with the cleaning of the stove whilst it was off display during May - June 2008.

Fig 5b Detail of structural damage and past restoration to a tin-glazed earthenware tile. The break across the centre, restored in the past

Fig 5b Detail of structural damage and past restoration to a tin-glazed earthenware tile. The break across the centre, restored in the past, is unsightly but secure.

Individual tiles had vulnerable areas of damage that required students to make further considered judgements. Some areas of the glaze have flaked off the surface exposing the ceramic body, leaving the glaze edges vulnerable to further damage - often requiring cleaning to be delayed until consolidation had taken place, to prevent further lifting of the glaze.

Fig 6 Detail of cleaning in progress: the intricate nature of the high relief-moulded decorative tiles requires methodical method of cleaning.

Fig 6 Detail of cleaning in progress: the intricate nature of the high relief-moulded decorative tiles requires methodical method of cleaning.

Fig 6 Detail of cleaning in progress: the intricate nature of the high relief-moulded decorative tiles requires methodical method of cleaning. Dampened cotton wool on a wooden swab stick  is rolled lightly across the surface to lift the dirt off the surface (a wiping motion can push dirt into any surface irregularities, cracks or chips rather than remove it).

Fig 7, The team of students cleaning the object during spring 2008.

Fig 7, The team of students cleaning the object during spring 2008.

A team of three to four students, accompanied by a course tutor, travelled to London over a period of a few weeks to undertake the initial treatment procedures. A different team of students was welcomed on each visit.

Fig 8 The team of students cleaning the object during spring 2008.

Fig 8 The team of students cleaning the object during spring 2008.

The students were briefed on the project and work requirements at the start of each day.

Fig 9 The team of students cleaning the object during spring 2008.

Fig 9 The team of students cleaning the object during spring 2008.

Guidelines on dry and wet cleaning methods were provided and discussed. The students had to work well as a team to make the most productive use of the time available.

Fig 10 The team of students cleaning the object during spring 2008.

Fig 10 The team of students cleaning the object during spring 2008.

They had to be able to accept the restrictions given - the challenge was not so much in the treatment process but in applying good working principles.

Fig 11 The team of students cleaning the object during spring 2008.

Fig 11 The team of students cleaning the object during spring 2008.

A consistent level of finish needed to be reached within a given amount of time.

Fig 11 The team of students cleaning the object during spring 2008.

Fig 11 The team of students cleaning the object during spring 2008.

Fig 11 The team of students cleaning the object during spring 2008 - another detail of the object.

Fig 12 A painted carved wood leg acts as a replacement for the missing ceramic component. Detail of the wooden leg during surface cleaning.

Fig 12 A painted carved wood leg acts as a replacement for the missing ceramic component. Detail of the wooden leg during surface cleaning.

There are also numerous areas of old retouched plaster or resin fills and painted wooden components that are to remain in place and these required cleaning tests to be undertaken before treatment.